Degree: The number of edges connected to a node

Strength: The cummulative weight of all the edges connected to a node

Betweeness: Defined by the number of shortest paths going through an edge

Closeness: Defined by the number of steps required to access every other vertex from a given vertex

Authority Score: Defined by the number of Hubs pointing to the node

Hub Score: Defined by the number of Authorities the node points to

Google interprets a link from page A to page B as a vote, by page A, for page B … Votes cast by pages that are themselves ‘important’ weigh more heavily and help to make other pages ‘important.’